scholarly journals Interannual fluctuations in the seasonal cycle of nitrous oxide and chlorofluorocarbons due to the Brewer-Dobson circulation

2013 ◽  
Vol 118 (19) ◽  
pp. 10,694-10,706 ◽  
Author(s):  
P. G. Simmonds ◽  
A. J. Manning ◽  
M. Athanassiadou ◽  
A. A. Scaife ◽  
R. G. Derwent ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Seasonal Cycle ◽  
Interannual Fluctuations

scholarly journals Global reconstruction reduces the uncertainty of oceanic nitrous oxide emissions and reveals a vigorous seasonal cycle

2020 ◽  
Vol 117 (22) ◽  
pp. 11954-11960 ◽  
Author(s):  
Simon Yang ◽  
Bonnie X. Chang ◽  
Mark J. Warner ◽  
Thomas S. Weber ◽  
Annie M. Bourbonnais ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Seasonal Cycle ◽  
Coastal Upwelling ◽  
Learning Algorithm ◽  
Southern Oscillation ◽  
Latitudinal Gradients ◽  
Nitrous Oxide Emissions ◽  
Boreal Summer ◽  
Intergovernmental Panel ◽  
Tropical Ocean

Assessment of the global budget of the greenhouse gas nitrous oxide (N2O) is limited by poor knowledge of the oceanicN2O flux to the atmosphere, of which the magnitude, spatial distribution, and temporal variability remain highly uncertain. Here, we reconstruct climatologicalN2O emissions from the ocean by training a supervised learning algorithm with over 158,000N2O measurements from the surface ocean—the largest synthesis to date. The reconstruction captures observed latitudinal gradients and coastal hot spots ofN2O flux and reveals a vigorous global seasonal cycle. We estimate an annual meanN2O flux of 4.2 ± 1.0 Tg N⋅y−1, 64% of which occurs in the tropics, and 20% in coastal upwelling systems that occupy less than 3% of the ocean area. ThisN2O flux ranges from a low of 3.3 ± 1.3 Tg N⋅y−1in the boreal spring to a high of 5.5 ± 2.0 Tg N⋅y−1in the boreal summer. Much of the seasonal variations in globalN2O emissions can be traced to seasonal upwelling in the tropical ocean and winter mixing in the Southern Ocean. The dominant contribution to seasonality by productive, low-oxygen tropical upwelling systems (>75%) suggests a sensitivity of the globalN2O flux to El Niño–Southern Oscillation and anthropogenic stratification of the low latitude ocean. This ocean flux estimate is consistent with the range adopted by the Intergovernmental Panel on Climate Change, but reduces its uncertainty by more than fivefold, enabling more precise determination of other terms in the atmosphericN2O budget.

scholarly journals Exploring causes of interannual variability in the seasonal cycles of tropospheric nitrous oxide

2011 ◽  
Vol 11 (8) ◽  
pp. 3713-3730 ◽  
Author(s):  
C. D. Nevison ◽  
E. Dlugokencky ◽  
G. Dutton ◽  
J. W. Elkins ◽  
P. Fraser ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Interannual Variability ◽  
Empirical Evidence ◽  
Southern Hemisphere ◽  
Seasonal Cycle ◽  
Coastal Upwelling ◽  
Transport Model ◽  
Seasonal Cycles ◽  
Stratospheric Temperature

Abstract. Seasonal cycles in the mixing ratios of tropospheric nitrous oxide (N2O) are derived by detrending long-term measurements made at sites across four global surface monitoring networks. The detrended monthly data display large interannual variability, which at some sites challenges the concept of a "mean" seasonal cycle. In the Northern Hemisphere, correlations between polar winter lower stratospheric temperature and detrended N2O data, around the month of the seasonal minimum, provide empirical evidence for a stratospheric influence, which varies in strength from year to year and can explain much of the interannual variability in the surface seasonal cycle. Even at sites where a strong, competing, regional N2O source exists, such as from coastal upwelling at Trinidad Head, California, the stratospheric influence must be understood to interpret the biogeochemical signal in monthly mean data. In the Southern Hemisphere, detrended surface N2O monthly means are correlated with polar spring lower stratospheric temperature in months preceding the N2O minimum, providing empirical evidence for a coherent stratospheric influence in that hemisphere as well, in contrast to some recent atmospheric chemical transport model (ACTM) results. Correlations between the phasing of the surface N2O seasonal cycle in both hemispheres and both polar lower stratospheric temperature and polar vortex break-up date provide additional support for a stratospheric influence. The correlations discussed above are generally more evident in high-frequency in situ data than in data from weekly flask samples. Furthermore, the interannual variability in the N2O seasonal cycle is not always correlated among in situ and flask networks that share common sites, nor do the mean seasonal amplitudes always agree. The importance of abiotic influences such as the stratospheric influx and tropospheric transport on N2O seasonal cycles suggests that, at sites remote from local sources, surface N2O mixing ratio data by themselves are unlikely to provide information about seasonality in surface sources, e.g., for atmospheric inversions, unless the ACTMs employed in the inversions accurately account for these influences. An additional abioitc influence is the seasonal ingassing and outgassing of cooling and warming surface waters, which creates a thermal signal in tropospheric N2O that is of particular importance in the extratropical Southern Hemisphere, where it competes with the biological ocean source signal.

scholarly journals Stratospheric influence on the seasonal cycle of nitrous oxide in the troposphere as deduced from aircraft observations and model simulations

2010 ◽  
Vol 115 (D20) ◽  
Author(s):  
Kentaro Ishijima ◽  
Prabir K. Patra ◽  
Masayuki Takigawa ◽  
Toshinobu Machida ◽  
Hidekazu Matsueda ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Seasonal Cycle ◽  
Model Simulations ◽  
Aircraft Observations

scholarly journals Abiotic and biogeochemical signals derived from the seasonal cycles of tropospheric nitrous oxide

2010 ◽  
Vol 10 (11) ◽  
pp. 25803-25839
Author(s):  
C. D. Nevison ◽  
E. Dlugokencky ◽  
G. Dutton ◽  
J. W. Elkins ◽  
P. Fraser ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Interannual Variability ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Coastal Upwelling ◽  
Seasonal Cycles ◽  
Mixing Ratios ◽  
Stratospheric Temperature ◽  
Deep Ocean Water

Abstract. Seasonal cycles in the mixing ratios of tropospheric nitrous oxide (N2O) are derived by detrending long-term measurements made at sites across four global surface monitoring networks. These cycles are examined for physical and biogeochemical signals. The detrended monthly data display large interannual variability, which at some sites challenges the concept of a "mean" seasonal cycle. The interannual variability in the seasonal cycle is not always correlated among networks that share common sites. In the Northern Hemisphere, correlations between detrended N2O seasonal minima and polar winter lower stratospheric temperature provide compelling evidence for a stratospheric influence, which varies in strength from year to year and can explain much of the interannual variability in the surface seasonal cycle. Even at sites where a strong, competing, regional N2O source exists, such as from coastal upwelling at Trinidad Head, California, the stratospheric influence must be understood in order to interpret the biogeochemical signal in monthly mean data. In the Southern Hemisphere, detrended surface N2O monthly means are correlated with polar lower stratospheric temperature in months preceding the N2O minimum, suggesting a coherent stratospheric influence in that hemisphere as well. A decomposition of the N2O seasonal cycle in the extratropical Southern Hemisphere suggests that ventilation of deep ocean water (microbially enriched in N2O) and the stratospheric influx make similar contributions in phasing, and may be difficult to disentangle. In addition, there is a thermal signal in N2O due to seasonal ingassing and outgassing of cooling and warming surface waters that is out of phase and thus competes with the stratospheric and ventilation signals. All the seasonal signals discussed above are subtle and are generally better quantified in high-frequency in situ data than in data from weekly flask samples, especially in the Northern Hemisphere. The importance of abiotic influences (thermal, stratospheric influx, and tropospheric transport) on N2O seasonal cycles suggests that, at many sites, surface N2O mixing ratio data by themselves are unlikely to provide information about seasonality in surface sources (e.g., for atmospheric inversions), but may be more powerful if combined with complementary data such as CFC-12 mixing ratios or N2O isotopes.

Severe gastrointestinal distension during nitrous oxide and oxygen anesthesia

JAMA ◽  
1965 ◽  
Vol 194 (10) ◽  
pp. 1146-1148 ◽  
Author(s):  
F. F. Foldes
Keyword(s):  
Nitrous Oxide
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